The Fantasy Zone is a solar system consisting of eight brightly colored, fantastic planets. The evil Menons are trying to take over all of the planets in the Fantasy Zone by using misappropriated foreign currency to build their forces. It is the player's job to recover all of the coins and save the solar system! The Fantasy Zone is an arcade-style shooter for one or two players. The goal is to destroy all of the creatures on each planet and collect as many of the lost coins as possible. To be allowed to battle the boss of a level, the player will have to locate ten enemy bases with the help of their radar and then destroy them. Defeating the boss enemy will then allow the player to move on to the next world. At various points in the game, the player will be able to find a parts shop, which allows purchasing improvements for his spaceship, including better weapons and faster engines.
Some differences worth noting when comparing the original arcade version with its ports include:
The Sega Master System and MSX versions lack the base location radar, have six bases per stage instead of ten, and feature different bosses compared to the original. The NES Sunsoft version has only eight bases per stage instead of ten. The NES Tengen version also has only six bases per stage instead of ten. The Sharp X68000 version includes an arrange mode where the bases drop letters in the word Harrier, and spelling Harrier correctly will reward the player with an extra Space Harrier-themed level called Dragon Land. This level allows the player to battle all the bosses from that game. The 3DS version features game options such as setting the number of lives, difficulty level, and firing speed of the ships' weapons, allowing for more flexibility in gameplay. Coins can also be carried over to subsequent games and added to a coin stock.
This version includes an unlockable Upa-Upa mode where the player controls Opa-Opa's brother, with unique features such as switching between weapons on the fly. The game also has a unique ending that differs from the original version, and an additional unlockable replaces two of the Arcade version bosses with Sega Master System versions.